An ultrahigh performance InGaN/GaN visible-light phototransducer based on polarization induced heterointerface barrier and minority carrier localization

Abstract

With the emergence of new applications such as underwater optical communication, the demand for photodetectors with high responsivity, high speed and wavelength selectivity is growing. These performances require gain-type photodetectors based on materials other than Si. The complexity of device structure and process, however, makes almost all gain-type photodetectors based on less-mature materials unsuitable for application in reality despite their demonstrated high performance. Here, a simple InGaN/GaN phototransducer is proposed for high-performance visible-light photodetection using the interface polarization barrier and minority carrier localization in pseudocrystalline InGaN/GaN heterostructures. The polarization induced negative charges at the InGaN/GaN heterointerface increase the interface potential and form a bidirectional potential barrier. This barrier hinders carrier transport in the absence of irradiation, and localizes photogenerated holes under visible-light illumination, thereby lowering the barrier height and generating a high photoinduced gain. The resulting phototransducers exhibit an ultrahigh responsivity of ∼1.3 × 10⁴ A W⁻¹, a large specific detectivity of 1.2 × 10¹⁵ Jones, and an ultrafast response with a rising/falling time of 2.2 ns/3.1 μs at 3 V. The proposed device with a simple structure and fabrication process, therefore, provides another feasible path for high-performance photodetection in addition to the gain-photodetector with a Schottky barrier or a pn junction as the building block.